Methods and apparatus for intraluminal placement of a bifurcated intraluminal graft

ABSTRACT

Methods and apparatus for placing a bifurcated aortic graft, with extensions, into a body lumen. An aortic graft is provided with a unique combination of self-expanding a balloon expandable wires. The aortic graft is bifurcated and includes ipsilateral and contralateral legs. Two extension grafts are provided for frictional engagement with the legs of the aortic graft. For placement of the bifurcated aortic graft with extensions, an introducer assembly including a dilator and a sheath assembly provides access for the introduction of a main catheter and a directional catheter. The main catheter is provided for deployment of the bifurcated aortic graft within the lumen of a vessel. A balloon is provided on the main catheter for expanding the balloon-expandable wires of the aortic graft. The directional catheter, which includes a deflecting spring portion, permits placement of a guidewire through the ipsilateral leg and into the contralateral leg of the aortic graft. In turn, a second introducer sheath and a second catheter assembly are provided contralaterally for introduction of a graft extension. Upon balloon-expansion, the graft extension is frictionally engaged with the contralateral leg of the aortic graft. A third catheter assembly including a second extension graft is provided for introduction of the extension graft and balloon-expansion thereof for frictional engagement with the ipsilateral leg of the graft.

RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of co-pendingU.S. application Ser. no. 09/163,580, filed Sep. 30, 1998 under the sametitle.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is directed generally to methods andapparatus for positioning an intraluminal graft. More specifically thepresent invention is related to methods and apparatus for positioning anintraluminal graft into a bifurcating vessel such as an artery.

[0004] 2. Discussion of Related Technology

[0005] An artery or other vessel that is weakened by disease, injury, orcongenital defect, can become distended due to the pressure of blood orother fluid flowing through the weakened area. In the vasculature, thisdistended weakening is called an aneurysm. An aneurysm typically occursin the arterial vessels of the head, chest, or abdomen. The distensionmay cause the vessel to rupture, which can have serious, evenlife-threatening consequences.

[0006] Aneurysms in the abdominal aorta are typically distended aroundthe circumference of the aorta and tapered at both ends. Most aneurysmsof the abdominal aorta are caused by atherosclerotic weakening of asegment of the wall. Abdominal aneurysms may cause backache and severepain, and may be visible as a throbbing swelling. If an abdominal aortaruptures, it is seriously life threatening.

[0007] Traditionally, aneurysms have been treated by radical surgicalgraft replacement. This approach is risky for the patient and issometimes not feasible due to other pre-existing disease states of thepatient. More recently, aneurysms have been treated by placement of anintraluminal or endovascular graft. These intraluminal or endovasculargrafts may be of various types, including grafts having stents,wireforms, or other attachment means attached to or integrated into thegraft structure.

[0008] In general, intraluminal grafts and their respective supportand/or attachment means fall into two major categories, self-expandingand pressure expandable. Self-expanding intraluminal grafts, aresupported and/or attached via resilient or shape-memory material such asspring steel or Nitinol™. Self-expanding material is capable of beingformed in a configuration from which it may be compressed to a radiallycompact diameter for placement within a damaged vessel. At the time ofuse, the memory feature of these materials causes them to self-expandfrom the radially compact diameter to the expanded operative diameter.

[0009] Pressure-expandable intraluminal grafts are supported and/orattached via plastically deformable material such as stainless steelthat is initially formed in its radially compact diameter. This type ofmaterial does not have memory, and will remain in the radially compactdiameter until manually expanded. Typically, outwardly directed pressureis exerted upon the graft through use of a balloon so as to cause radialexpansion and resultant plastic deformation of the material to itsoperative diameter.

[0010] Careful positioning and firm implantation of the intraluminalgraft is critical to the successful treatment of the underlying medicalcondition. This is particularly difficult to accomplish when theaneurysm extends from an artery into one or more divergent arteries. A“trouser graft” has been suggested for use in a first main artery and apair of divergent arteries by White et al. in PCT Application Nos. WO97/17910; WO 97/17911; WO 97/18006; WO 97/26936; and WO 97/26938; all ofwhich are hereby incorporated herein by reference in their entireties. Atrouser graft comprises a first tubular body that bifurcates into twosmaller tubular bodies. In the referenced disclosures, the first tubularbody is placed in first artery and the two smaller tubular bodies areplaced so as to extend within the two divergent arteries.

[0011] Notwithstanding the important teachings of the foregoingreferences, features of the aforementioned device have recognizedshortcomings that make them less than complete solutions to thetreatment of aneurysms in the vasculature, or to the treatment ofsimilar damage to other vessels. The present invention providessubstantial improvements to the methods and apparatus of the prior art.

SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to provide an improvedintraluminal graft and method for placement of same that diminishesdeleterious kinking and twisting of the graft during and after placementthereof in a vessel.

[0013] It is another object of the present invention to provide animproved intraluminal graft and method for placement of same thatprovides control over inadvertent longitudinal movement within a vessel.

[0014] Another object of the present invention is to provide an improvedintraluminal “trouser” graft and method for placement of same thatprecludes inadvertent separation of the legs of the trouser.

[0015] These and other objects and features of the present inventionwill become more fully apparent from the following description andappended claims, or may be learned by the practice of the invention asset forth hereinafter.

[0016] To achieve the forgoing objects, and in accordance with theinvention as embodied and broadly described herein, the presentinvention relates to new and useful apparatus and methods for placing abifurcated graft at the site of a damaged vessel. In a preferredembodiment, the methods and apparatus of the present invention aredirected to placement of a bifurcated graft within an aneurysm locatedin the abdominal aorta downstream of the renal arteries. Preferably,placement of the graft is through the right femoral artery of a patient.

[0017] An introducer assembly is provided which is configured forplacement over a guidewire and for facilitating the advancement ofvarious catheter assemblies required in connection with the practice ofthe invention. The introducer assembly includes a sheath, valve head,and a dilator. The sheath is preferably cylindrical in shape and isformed so as to have an appropriate flexibility and an outer diametersuitable for placement at the location of an aneurysm to be repaired.The valve head permits insertion and removal of various catheters duringthe method of the present invention without significant loss of bloodfrom the femoral artery. The proximal end of the valve head is providedwith a threaded connector which facilitates connection of the valve headto other catheters. The dilator, which includes a tapered tip, is placedduring use through the valve head and the sheath so that the tapered tipportion protrudes from the sheath. The dilator tip portion is capable ofbeing advanced gently through the tortuous pathway of the vasculaturewithout causing undue trauma or a perforation, yet is also sufficientlystiff to cause the blood vessels to assume a less tortuous path.

[0018] Another component of the present invention is a bifurcated aorticgraft. The preferred bifurcated aortic graft includes bothself-expanding and balloon-expandable wireforms along its length. Theballoon-expandable wires permit precision in placement of the aorticgraft. The self-expanding wires open within the vessel immediately upondeployment from the main catheter assembly, which allows insertion ofother modular components, opens a removal path for the inflatableballoons, and reduces kinking. The self-expanding wires also increasethe anchoring force between the bifurcated graft and modular extensiongrafts used to extend the bifurcated graft into communication withnon-distended vessel walls.

[0019] One of the self-expanding wireforms is located at a septum regionof the bifurcated graft. The septum region separates an ipsilateral legfrom a contralateral leg (“ipsilateral” and “contralateral” referring toopposite lateral sides of the patient depending on the surgicalapproach). This septum wire prevents and helps eliminate the kinks thatare typically encountered with conventional bifurcated grafts. Inaddition, the self-expanding wireform at the septum region includescrimps functioning as radiopaque markers generally pointing to theseptum region, which aids in identifying the location of the septumunder fluoroscopy. Two additional self-expanding wireforms are locatedat the ends of each leg of the bifurcated graft. These wireformsfacilitate opening the legs immediately upon deployment from the maincatheter assembly to allow for the insertion of modular components.These leg wireforms also contain crimps as radiopaque markers which aidin identifying the ends of the bifurcated graft legs. All crimps on theself-expanding wireforms are placed on the anterior side of the graft,thus aiding in orientation of the graft under fluoroscopy.

[0020] The main catheter assembly is utilized to place the aortic graftdescribed above, which is compressed and loaded onto the distal end ofthe main catheter assembly. The main catheter assembly is sized suchthat it will fit inside the introducer sheath.

[0021] The components of the main catheter assembly include thefollowing: a rigid loader configured for connection to the valve head ofthe sheath assembly; a proximal connector assembly including a distalpusher connector; an elongate, tubular pusher body; an elongate catheterwith a coaxial tube construction; and an inflatable catheter balloon.

[0022] In addition to the aortic graft, two additional graft portionsare adapted to extend into the respective iliac arteries to form africtional engagement with the ipsilateral and contralateral legs of theaortic graft. These extension grafts typically comprise straightcylindrical tubes, with an upstream end having a common diameter. Theupstream ends interlock with the respective downstream portions of theaortic graft.

[0023] The present invention may further include a directional catheterwhich permits placement of the graft extensions. The directionalcatheter includes a deflecting spring portion, a knob used to deflectthe spring portion, and a connector nut for connection with the sheathassembly.

[0024] The preferred method for using the aforementioned components ofthe present invention includes the following steps. An incision is madeand a primary guidewire is placed in conventional fashion in theipsilateral side, that is, for example, through the right femoral arteryand the right common iliac artery so as to extend well upstream of theaneurysm. The introducer assembly is advanced over and along the primaryguidewire into a position upstream of the renal arteries. Once thesheath of the introducer assembly has been properly placed, the dilatoris retracted along the guidewire and then completely removed from withinthe sheath assembly and from primary guidewire. The main catheterassembly is inserted over the primary guidewire and into the sheathassembly, and then connected thereto. The pusher body is distallyadvanced to push the aortic graft and main catheter through to the endof the introducer sheath. The sheath containing the aortic graft is thenretracted slowly to approximately a desired deployment position in theabdominal aorta. The introducer sheath is then retracted to a positionjust below the septum region, freeing the aortic graft and exposing itto blood flow.

[0025] The balloon-expandable, upstream portion of the aortic graftremains in a substantially compressed configuration. The catheterballoon is inflated which facilitates the concurrent radial expansion ofthe balloon-expandable portions of the graft from the initial, collapsedorientation, to the second, expanded orientation. In one embodiment ofthe present invention, the graft is slightly over-sized to optimizeengagement of the aortic graft with the aortic wall. When the graft isfully expanded, the upstream end thereof frictionally engages theluminal surfaces of unaffected regions of the aorta just below the renalarteries. After the graft has been radially expanded in theaforementioned manner, the balloon is deflated, longitudinally stretchedto prevent snagging on the graft, and then removed. The main catheter isthen withdrawn slowly and carefully, with the introducer sheath and theprimary guidewire remaining in place.

[0026] For placement of the graft extensions, the directional catheteris first inserted over the primary guidewire. The spring portion of thedirectional catheter is positioned such that it is above the septumregion of the aortic graft. The spring portion is deflected by pullingproximally on the knob. A supplemental guidewire is then advancedthrough the directional catheter and out the deflected spring portionsuch that the supplemental guidewire extends down the contralateral legand through the left common iliac artery. The supplemental guidewire isextended until it is in the left femoral artery, at which time the leftfemoral artery is cross-clamped and a cut-down or percutaneous incisionis performed to retrieve the supplemental guidewire. Once the guidewireis retrieved, a stiffer guidewire is exchange through the left femoralartery until it is within the first graft and reaches the contralateralside of the aortic graft. A second introducer assembly is thenintroduced over the stiff guidewire.

[0027] A second catheter assembly on which is packaged a tubular graftextension is then introduced through the second sheath assembly untilthe introducer sheath extends through the left iliac artery andterminates at the bifurcation point of the aortic graft. The sheathfollowed by the pusher of the second catheter assembly are then pulledback proximally to release the tubular graft extension. The balloon onthe second catheter assembly is then inflated such that the upstream endof the extension graft is frictionally engaged with the downstreamcontralateral leg of the aortic graft. In one embodiment of the presentinvention, the extension graft is slightly over-sized such that itoptimally engages with the self-expanding downstream contralateral leg.The balloon is then deflated and the second catheter assembly is removedin the manner previously described hereinabove with respect to the maincatheter.

[0028] The directional catheter is also removed such that a thirdcatheter assembly, on which is packaged a tubular graft extension, andwhich may be identical to the second catheter assembly, can beintroduced over the primary guidewire and through the first introducersheath assembly. This third catheter assembly is advanced until thedistal end of the extension graft is at the bifurcation point of theaortic graft. In like manner to that previously described, a third graftextension positioned on the third catheter assembly is deployed suchthat its upstream end is in contact with the ipsilateral leg of theaortic graft, and its downstream end is in contact with the right iliacartery. Also as previously described, the balloon on third catheterassembly is inflated to expand the balloon expandable extension graft inthe ipsilateral side. In one embodiment of the present invention, theextension graft is slightly over-sized such that it optimally engageswith the self-expanding downstream ipsilateral leg. Finally, the balloonis deflated and stretched, and the third catheter assembly is withdrawn.

[0029] In an alternate embodiment both the ipsilateral and contralateralballoon catheters could be positioned simultaneously and inflatedsequentially. While maintaining the position of the third catheterballoon the second catheter balloon is deflated and stretched and thesecond catheter is removed. The third catheter balloon is subsequentlydeflated, stretched, and removed.

[0030] The second sheath assembly and the stiff guidewires are withdrawnand the contralateral incision or puncture is sutured. An angiographicexamination may take place to determine if the grafts are correctlyplaced and functioning. The first introducer sheath assembly iswithdrawn and the right femoral incision is sutured. The result is afunctioning trouser graft bridging an aneurysm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more fully understand the manner in which the above-recitedand other advantages and objects of the invention are obtained, a moreparticular description of the invention will be rendered by reference toa specific embodiment thereof which is illustrated in the appendeddrawings. Understanding that these drawings depict only a typicalembodiment of the invention and are not therefore to be considered to belimiting of its scope, the invention in its presently understood bestmode for making and using the same will be described and explained withadditional specificity and detail through the use of the accompanyingdrawings in which:

[0032]FIG. 1 is a front view of an aortic graft in accordance with thepresent invention;

[0033]FIG. 1A is a perspective view of a cylindrical mandrel for formingthe self-expanding wires of FIG. 1;

[0034]FIG. 1B is a partial plan view of an alternate configuration for aballoon-expandable wireform in accordance with the present invention;

[0035]FIG. 2 is front view of a graft extension in accordance with thepresent invention;

[0036]FIG. 2A is an internal cross-sectional view of the graft extensionfrom FIG. 2;

[0037]FIG. 3 is an exploded perspective view of an introducer assemblyof the present invention;

[0038]FIG. 4 is a perspective view of a main catheter assembly of thepresent invention;

[0039]FIG. 5 is a front perspective view of a directional catheterassembly of the present invention;

[0040]FIG. 6 is a side view of the main catheter assembly of FIG. 4 withthe expandable balloon shown exposed and in an expanded configuration;

[0041]FIG. 7A is a partial perspective view of the main catheterassembly being inserted into the introducer assembly;

[0042]FIG. 7B is a partial perspective view of the main catheterassembly connected to the introducer assembly;

[0043]FIG. 8A is a schematic cutaway view of the abdominal region of thehuman body (“schematic abdominal view”) having a guidewire positionedtherein;

[0044]FIG. 8B is a sectional view of an abdominal aorta and aneurysm(“sectional aneurysmic view”) having a guidewire positionedtherethrough;

[0045]FIG. 9A is a schematic abdominal view having an introducerassembly positioned therein;

[0046]FIG. 9B is a sectional aneurysmic view having an introducerassembly positioned therethrough;

[0047]FIG. 9C is a schematic abdominal view with an introducer sheathpositioned above the renal arteries and the dilator removed therefrom;

[0048]FIG. 10A is a schematic abdominal view with the balloon of themain catheter assembly and aortic graft advanced within the introducersheath to the renal arteries;

[0049]FIG. 10B is a sectional aneurysmic view similar to FIG. 10A;

[0050]FIG. 10C is a detailed view of the introducer sheath beingwithdrawn to expose the aortic graft therein;

[0051]FIG. 10D is a sectional aneurysmic view with the introducer sheathwithdrawn to a position downstream of the aortic graft;

[0052]FIG. 11A is a schematic abdominal view with the balloon of themain catheter assembly expanded within a trunk portion of the aorticgraft;

[0053]FIG. 11B is a schematic abdominal view with the balloon of themain catheter assembly over-expanded within the aortic graft trunkportion;

[0054]FIG. 12A is a schematic abdominal view with the balloon of themain catheter assembly deflated within the aortic graft;

[0055]FIG. 12B is a sectional aneurysmic view with the deflated balloonon the main catheter assembly being stretched to facilitate removal frominside the aortic graft;

[0056]FIG. 12C is a schematic abdominal view with the main catheterassembly being withdrawn therefrom and only the main guidewire extendingthrough the aortic graft;

[0057]FIG. 13A is a schematic abdominal view with the directionalcatheter connected to the sheath assembly and positioned within theaortic graft;

[0058]FIG. 13B is a detailed view of the directional catheter beingdeflected around the septum region of the aortic graft;

[0059]FIG. 13C is a sectional aneurysmic view with the directionalcatheter advanced to a position above the renal arteries and a secondguidewire positioned within the contralateral side;

[0060]FIG. 14A is a schematic abdominal view with a second catheterassembly positioned within the contralateral side;

[0061]FIG. 14B is a sectional aneurysmic view with a second introducersheath positioned at the septum region and the dilator removedtherefrom;

[0062]FIG. 15A is a sectional aneurysmic view of a balloon of the secondcatheter assembly and an associated first extension graft advancedwithin the second introducer sheath to the septum region;

[0063]FIG. 15B is a sectional aneurysmic view with the second introducersheath withdrawn to a position downstream of the now exposed firstextension graft;

[0064]FIG. 15C is a sectional aneurysmic view with the first extensiongraft from FIG. 15B being expanded from inflation of the balloon on thesecond catheter assembly;

[0065]FIG. 16A is a sectional aneurysmic view with a balloon of a thirdcatheter assembly and an associated second extension graft advancedwithin the first introducer sheath on the ipsilateral side to the septumregion of the aortic graft;

[0066]FIG. 16B is a sectional aneurysmic view with the first introducersheath withdrawn to a position downstream of the now exposed secondextension graft;

[0067]FIG. 16C is a cross-section along line 16C-16C of FIG. 16B; and

[0068]FIG. 16D is a sectional aneurysmic view with a fully deployedaortic graft and first and second graft extensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] The present invention enables placement of a bifurcated graft ata site of a damaged vessel, such as an artery, by minimally invasivetechniques rather than an open surgical access route. Although themethods and apparatus of the present invention are applicable forvarious types of body lumens, the description herein will be directed toplacement of a bifurcated graft within an aneurysm located in theabdominal aorta downstream of the renal arteries for purposes of brevityand simplicity.

[0070] In addition, a particular procedure is described herein showingplacement of the graft through the right femoral artery of a patient.This method is presently preferred for several reasons. For example, itis contemplated that the bifurcated graft of the present invention willbe placed by a vascular surgeon, interventional radiologist or acardiologist. As a practical matter, physicians are accustomed toplacing catheters through a femoral artery entry point, and are lessaccustomed to other entry points. Further, since most physicians areright handed, the preferred insertion will be in the right femoralartery. By describing this type of insertion, however, it is notintended to exclude other insertion locations, such as the leftsubclavian artery, or the initiation of the procedure through the leftfemoral artery. Those of ordinary skill will be able to take theteachings herein and apply them to other body lumens, other lumenlocations, and other insertion sites.

[0071] As the terms are used herein with reference to the human body,“upstream” pertains to the direction towards the heart while“downstream” pertains to the direction away from the heart. Whenreferring to catheters, “distal” refers to the tip of catheter that isinserted into a patient and “proximal” refers to the end of the catheteroutside the body of a patient. The orientation of the graft of thepresent invention will be referenced with respect to whether it iscarried by the catheter or implanted at the aneurysm site, Specifically,upstream and downstream will be used to refer to the portions of theimplanted graft closer and farther from the heart, respectively.Alternatively, when the graft is still carried on the catheter, distaland proximal will be used to refer to portions of the graft inaccordance with the aforementioned catheter orientation. Finally,ipsilateral refers to the side of the patient in which the primaryguidewire and main catheter are inserted (the right femoral artery inthe present embodiment), while contralateral refers to the oppositeside.

[0072] Aneurysms frequently form in the abdominal aorta at a locationbetween the renal arteries and immediately proximal to the common iliacarteries. FIG. 8A, for example, illustrates the anatomy of the abdomenin the location of an aortic aneurysm. The abdominal aorta 100 can beseen branching distally into the common iliac arteries, the right commoniliac artery 102 and the left common iliac artery 104. The right andleft renal arteries 106, 108 and the right and left kidneys 110, 112 arelocated proximal from the common iliacs 102, 104. In between the commoniliacs and the renal arteries, an aortic aneurysm 114 can be seen as abulging section of the abdominal aorta 100. Although not depicted in thepresent figure, such an aneurysm may even extend down one or both iliacarteries. The right and left common iliac arteries 102, 104 become theright and left femoral arteries 116, 118 in the region of the pelvis 98.

[0073] A. Introducer Assembly

[0074] It is important to introduce the bifurcated aortic graft of thepresent invention without causing damage to the patient's vasculature,without undue loss of blood, without dislodging plaque, and with minimumeffort. It is a feature of the present invention to utilize an“introducer assembly” to achieve these objectives.

[0075] The “introducer assembly” of the present invention is preferablyconfigured for placement over a guidewire. Portions of the introducerassembly are thereafter used to facilitate the advancement of variouscatheter assemblies required in connection with the practice of theinvention as described below. An introducer assembly useful in thepractice of the present invention is described in co-pending U.S. patentapplication Ser. No. 08/713,070 filed on Sep. 12, 1996, incorporatedherein by reference (the '070 Application).

[0076] The primary components of introducer assembly 130 may be observedby reference to FIG. 3. FIG. 3 depicts a sheath assembly 132. Sheathassembly 132 is comprised generally of a sheath 134 and a valve head136. Sheath 134 is preferably cylindrical in shape along those portionsof its length to be inserted into a patient. Sheath 134 is formed so asto have an appropriate flexibility and an outer diameter suitable forplacement at the location of an aneurysm to be repaired. Sheath 134 isprovided with a lumen having a diameter suitable to permit insertion ofthe graft sections and the various catheters described below. Tipportion 138 of sheath 134 is preferably curved so as to minimize anytrauma to tissue or tendency to dislodge plaque when the sheath isadvanced upstream into a patient's vasculature. As mentioned in the '070application, tip portion 138 is preferably fitted with a radiopaquemarker to assist in proper placement during use.

[0077] The femoral artery is a relatively high-pressure lumen. Sheath134 is fitted with valve head 136 in a fluid-tight fashion. Valve head136 permits insertion and removal of various catheters during the methodof the present invention without significant loss of blood from thefemoral artery.

[0078]FIG. 3 additionally illustrates a dilator 140 used initiallyduring the insertion of sheath 134 and during any subsequent upstreammovement of sheath 134. Dilator 140 is placed during use through valvehead 136 and sheath 134 so that tapered dilator tip portion 142protrudes from sheath tip portion 138. Dilator tip portion 142 is formedof a somewhat resilient material that is capable of being advancedgently through the tortured pathway of the vasculature without causingundue trauma or a perforation. Yet, it is desired that the tip portionbe sufficiently stiff to cause the blood vessels to assume a lesstortuous path. In other words, it is intended that the tip portionstraighten the vasculature so as to facilitate placement of the sheath.Dilator 140 is provided with a lumen therethrough capable of fittingover a guidewire.

[0079] The proximal end of valve head 136 is provided with a threadedconnector 144. This threaded connector facilitates fluid-tightconnection of the valve head to other catheters during the practice ofthe method of the invention, as discussed in greater detail below.

[0080] The method for insertion of the introducer assembly will now bedescribed. As illustrated in FIGS. 8A and 8B, an incision 120 is madeand a primary guidewire 128 is placed in conventional fashion in theright femoral artery 116 and right common iliac artery 102 so as toextend well upstream of the aneurysm 114.

[0081] As illustrated in FIGS. 3 and 9A, the introducer assembly 130(comprising the sheath assembly 132 and the dilator 140) is advancedover and along the primary guidewire 128. As the introducer assembly isadvanced, dilator tip portion 142 gently straightens the patient'svasculature in preparation for sheath 134. As seen in FIG. 9B, theintroducer assembly is advanced to the point where tip portion 138 ofthe sheath 134 is upstream from the desired site of graft placement.Specifically, the tip portion 138 is advanced upstream of one of the tworenal arteries 106 and 108 located most proximal to the heart. Underfluoro-visualization, a radiopaque marker 139 in sheath tip portion 138confirms proper placement with respect to the anatomical landmark of therenal arteries.

[0082] Once the sheath has been properly placed, the dilator 140 (FIG.3) is retracted along the guidewire and then completely removed fromwithin the sheath assembly 132 and from primary guidewire 128. Asillustrated in FIG. 9C, once the dilator 140 has been removed, the lumenof sheath 134 is available for placement of other catheters. Valve head136 (FIG. 7A) prevents substantial blood loss from sheath assembly 132.

[0083] B. Aortic Graft

[0084] The aortic graft is designed for introduction into the abdominalaorta with the use of the main loading catheter, which will be describedin more detail below. First, the preferred structure of the aortic graftwill be described with reference to FIG. 1.

[0085] As illustrated in FIG. 1, one presently preferred embodiment ofthe aortic graft is designated generally at 10. Such a bifurcated graft,sometimes referred to as a “trouser graft,” is adapted for insertiontransfemorally to the situs of an aortic aneurysm in the region wherethe iliac arteries branch from the abdominal aorta.

[0086] The aortic graft 10 includes a proximal trunk portion 12 and isbifurcated to define two proximal legs, a contralateral leg 14 and anipsilateral leg 16. In this preferred embodiment, the ipsilateral leg 16extends longer than the contralateral leg 14 to facilitate loading ofboth legs into a smaller diameter loader when self expanding wireformsare attached to the end of each leg. The length difference between thetwo legs corresponds to the height of the self-expanding wireform, sothat the self-expanding wireforms are not side by side within theloader. This reduces the overall bulk of the graft and permits loadinginto a smaller diameter loader. One of skill in the art will appreciate,however, that the relative lengths of the two graft legs may be adjusteddepending on the particular application for which the graft is to beused. This difference in leg lengths also aids in orientation of thebifurcated graft under fluoroscopy.

[0087] The aortic graft 10 is configured from a flexible tubularstructure 18 which is reinforced by wireforms 20 extendingcircumferentially around or woven into the tubular structure 18. Theflexible tubular structure 18 is foldable, and the wireforms 20 areradially compressible and expandable. Thus, the graft is configured tomove between an insertion diameter, in which state the graft may beinserted intraluminally into the aorta, and a larger, expanded diameter(illustrated in FIG. 1) in which state the graft may be secured withinthe aorta.

[0088] In the expanded state illustrated in FIG. 1, the trunk portion 12is generally cylindrical and has a trunk diameter 22 correspondinggenerally to the diameter of an average aorta. In this preferredembodiment, the trunk portion 12 may be configured to be a variety ofsizes, one of which is selected according to the size of the abdominalaorta of the patient into which the graft is to be implanted. It ispresently preferred to make grafts in which the trunk portion is sizedto an expansion diameter of 19, 21, 23, 25, 27, and 29 mm. These sizes,of course, are not limiting of the sizes which may be utilized inaccordance with the teachings of the present invention.

[0089] As can readily be seen upon inspection of the graft of FIG. 1,the trunk portion 12 defines a cylindrical tube through which fluid mayflow. At a septum region 28, the graft bifurcates into the two legportions 14, 16. The cylindrical tubes defined by the two leg portionsare in fluid communication with the trunk portion 12, therebyapproximating the internal configuration of the bifurcated junction ofthe aortic artery. The legs 14, 16 are cylindrical and have diameterswhich, in their expanded state, correspond to a fixed diameter to insurea constant interface between the legs and the upstream end of theextension grafts which will be described later. In this embodiment, thecontralateral leg 14 and the ipsilateral leg 16 have expanded diametersof 13 mm. Again, the magnitude of the expanded diameter of the legs 14,16 may be varied according to the desired interface between the legs andthe extension grafts. However the diameter of the legs is not dependenton the diameter of the trunk region. In prior art bifurcated wovengrafts, the leg diameter is one half the diameter of the trunk. Forexample, a 26 mm trunk would always bifurcate into two 13 mm legs, a 28mm graft would bifurcate into two 14 mm legs, a 24 mm graft wouldbifurcate into two 12 mm legs, etc. This is a function of how bifurcatedgrafts are typically woven.

[0090] In the present invention, the lower portion of the trunk regioncan be tapered either out or in to insure a constant diameter of thelegs regardless of the trunk diameter. For example, a 28 mm trunk wouldtaper down to 26 mm in its lower region prior to being bifurcated intotwo 13 mm legs. Similarly, a 24 mm trunk would taper out to 26 mm priorto being bifurcated into two 13 mm legs. This provides for a standardleg diameter regardless of the trunk diameter and insures a constantinterface and interlock between the bifurcated graft and the extensiongrafts regardless of the relative diameters of the trunk and thedownstream ends of the extension grafts.

[0091] An alternative embodiment of this invention would be to maintaina straight trunk through the bifurcation region and then taper the legseither out or in to maintain a constant downstream diameter.

[0092] The flexible tubular structure 18 is preferably made of a tube ofwoven polyester fabric. Although polyester is presently preferred, othermaterials may be utilized for the flexible tubular structure 18. Suchmaterials include but are not limited to expandedpolytetrafluoroethylene (ePTFE), coated polyester, porous polyurethane,silicone, and spun or woven polymeric fibers. One of skill in the art ofbiocompatible grafts will readily identify other materials suitable forapplication in the construction of the flexible tubular structure 18. Itis preferred that the tubular structure be made of a material which isporous, thereby allowing tissue ingrowth into the graft material and/orformation of an intimal layer, although for some applications it may bedesirable to make the tubular structure of a fluid impervious material.

[0093] Preferably, the fabric is woven into the tubular configuration,thereby eliminating seams or other internal protrusions which couldinterfere with blood flow or form locations for thrombi to occur. Byemploying a flexible fabric for the tubular structure 18, the fabricwill readily fold to accommodate radial contraction of the graft, suchas is necessary for intraluminal introduction of the graft.

[0094] In a preferred embodiment of the present invention, the fabrictubing of the graft and the wireforms therein can be over-sized withrespect to the first balloon used to expand the balloon-expandablewireforms. Due to the fact that there is a small amount of recoil thatoccurs in the balloon-expandable wireforms after expansion, it may bedesirable to re-expand these wireforms to more accurately retain thegraft within the vessel. If the fabric tubing of the graft and thewireforms have a diameter which is larger than the post-recoil diameterof the wireforms after their first expansion, the physician can use asecond, larger balloon to re-expand or over-expand theballoon-expandable wireforms such that upon recoil of the wireformstheir diameters are of the proper size for optimum retention of thegraft within the vessel.

[0095] This feature enables a surgeon to optimize the fit of a graftwithin a vessel without having to remove it and replace it with another.That is, a graft which upon first balloon-expansion may not sufficientlyengage with the wall of the vessel, may be subsequently over-expanded tooptimize the fit therein. For example, the fabric tubing of the graftmay have a diameter of 24 mm, while the balloon-expandable wireformshave a diameter of 24 mm. The graft is first inflated to 23 mm and thewireforms will recoil to 22 mm. If the physician chooses to furtherexpand the wireforms and more optimally retain the graft in the vessel,the physician will bring in a larger balloon which inflates to 25 mm.After recoil, the final wireform diameter will be 24 mm and the graftwill be in its fully opened state.

[0096] In accordance with a presently preferred embodiment of theinvention, a number of wireforms 20 are provided to furnish structuralrigidity to the graft and to secure the graft within the body lumen. Asillustrated in FIG. 1, aortic graft 10 includes two different types ofwireforms: balloon-expandable wireforms 30 and self-expanding wireforms32. This preferred embodiment includes three balloon expandablewireforms 34, 36, and 38, which are woven into the fabric but positionedprimarily on the interior of the fabric in the trunk region 12 and asingle balloon-expandable wireform 40 positioned on the exterior of thefabric at the distal end of the trunk region 12. A self-expandingwireform 42 is attached to the outside of the fabric at the septumregion 28 with a self-expanding wireform 44 positioned on the distal endof the contralateral leg 14 and another self-expanding wireform 46 atthe distal end of the ipsilateral leg 16.

[0097] The balloon-expandable wireforms 30 of the present invention arepreferably made of an alloy of carbon, silicon, phosphorus, sulphur,chromium, nickel, beryllium, cobalt, iron, manganese and molybdenumwhich is sold under the ELGILOY trade name by Elgiloy, L.P. of Elgin,Ill., U.S.A. Other materials which may be utilized in making thewireforms 30 include a nickel and titanium alloy sold under the NITINOLtrade name, stainless steel, and other biocompatible, implantablemetals. The wires used in manufacturing the balloon-expandable wireforms30 of the present invention are preferably about 0.012 inches indiameter.

[0098] Preferably, each of the balloon-expandable wireforms 30 issimilarly configured with a curvilinear geometry such as the closedsinusoidal-like wave geometry illustrated in FIG. 1, with alternatingcrests 50 and valleys 52 which define an amplitude 54. The amplitude 54of a wireform is thus defined as the longitudinal distance between acrest 50 and an adjacent valley 52. In this preferred embodiment, theamplitude 54 of the proximal wireform 34 in its expanded state isapproximately 0.103 inches.

[0099] The balloon-expandable wireforms 30 are preferably configuredwith a plurality of intermediate segments 56 which are connected bycorresponding crests 50 and valleys 52. The crests 50 and valleys 52 areformed with a radius which, in this preferred embodiment, is about 0.025inches.

[0100] Preferably, the intermediate segments are positioned at an anglewith respect to each other of greater than about 90 degrees in order toprovide greater wireform rigidity, reduced wireform recoil and increasedanchoring force. To those ends the intermediate segments are morepreferably positioned at an angle with respect to each other from arange of about 100 degrees to about 135 degrees. Most preferably, theintermediate segments are positioned at an angle with respect to eachother from a range of about 120 degrees to about 125 degrees.

[0101] For example, in the most preferred embodiment, the crests 50 andvalleys 52 of the balloon-expandable wireforms 30 are configured byobtaining annealed ELGILOY wire having a diameter of preferably about0.012 inches and wrapping the wire around a pin having a diameter of0.050 inches, thereby defining a plurality of adjacent, intermediatesegments 56 positioned at an angle with respect to each other of fromabout 120 to 125 degrees. Thus, the amplitude of the intermediatesegments 56 of the proximal wireform 34 in its expanded state (i.e.,excluding the radius which defines the crests and valleys) is about0.103 inches. In this presently preferred embodiment, eachballoon-expandable wireform 40 has eight crests 50.

[0102] An alternative method for constructing the balloon-expandablewireforms 30 is to configure the wireforms in a true sinusoidal-likepattern. By constructing the wireforms 30 according to this alternativemethod, the angle between adjacent intermediate portions is about 120 to125 degrees, thereby maintaining the number of crests on the wireform toeight. Alternatively, the balloon-expandable wireforms are configuredsuch that they are continuously curvilinear as illustrated by FIG. 1B.This continuously curvilinear shape 48 primarily serves to reduce stresson the wireforms when the aortic graft is in its first, compressedstate. One of skill in the art will be familiar with other methods formanufacturing balloon-expandable wireforms without departing from theteachings of the present invention.

[0103] Because the wire has been annealed, it will readily plasticallydeform to maintain its configuration. Thus, the wireform may beplastically deformed between the radially collapsed position and theradially expanded position of FIG. 1. The wireforms are, therefore, notresilient to any substantial extent, requiring them to be physicallyexpanded into contact with the internal wall of the aorta via a forceother than their own resilience. Further, there is some amount of recoilafter balloon-expansion of the wireforms, which will be discussed inmore detail below.

[0104] The balloon-expandable wireforms 34, 36, and 38 which arepositioned along the proximal portion of the trunk 12 of the graft arepreferably secured to the fabric graft material by weaving the wireformthrough the fabric material. The wire is woven through the fabric suchthat the distal tip of the valley of each wireform extends through thegraft and is positioned on the outside of the fabric structure 18. Theweaving is accomplished by initially configuring an elongated piece ofwire into the predetermined curvilinear configuration. With the wire soconfigured, it may be manually woven through the fabric structure 18until the wire extends around the entire circumference of the fabricstructure 18. The wire is woven such that it is primarily positionedalong the interior of the fabric tube, with only small segments of wireexposed to the outside of the tube.

[0105] The wireform is woven into the fabric tube such that when thewire extends around the entire periphery of the fabric tube, the freeends of the wire protrude from the tube at positions adjacent to eachother, thereby enabling a tail segment 62 to be defined by the freeends. The loose ends are preferably held together with a crimping sleeve64 positioned over them. After crimping the sleeve to secure the ends toeach other and thereby complete the circular configuration of thewireform, any portion of the wires extending beyond the ends of thesleeve may be trimmed to cleanly finish the tail segment 62. It ispreferable that no portion of the wire extend beyond the edge of thecrimping sleeve to eliminate the possibility of the wire cutting orpiercing the lumen wall.

[0106] As illustrated in FIG. 1, the tail segments are positioned on theoutside of the fabric layer 18 and extend below the longitudinalposition of the other valleys 52 of the wireform. Thus, the mostproximal wireform 34 of FIG. 1 includes a tail segment 62 extending inthe distal direction below the level of adjacent valleys 52. Althoughthis configuration is preferred, one of skill in the art will appreciatethat the wireforms 30 may be formed in two parts with two tailspositioned on opposite sides of the graft.

[0107] The tail segments 62 of the balloon-expandable wireforms 30 arepreferably configured to extend substantially flat against the fabriclayer 18, i.e., substantially parallel to the longitudinal axis 60 ofthe graft. With the tail segments so configured, the risk that the tailsegments will penetrate or damage the wall of a lumen with which itcomes into contact will be substantially reduced.

[0108] The proximal wireform 34 is positioned with respect to the upperedge of the fabric layer such that approximately one-third of thewireform extends beyond the edge of the fabric layer. The wireform ispositioned to extend above the edge of the fabric layer to prevent anyportion of the fabric layer from oscillating, or “flapping,” in responseto the flow of blood past the edge of the graft. As an additionalmeasure to prevent such fabric oscillation in the blood stream, the edgeof the fabric is configured with V-shaped notches correspondinggenerally to the valleys 52 of the proximal wireform 34. Thus, the riskof the existence of any loose fabric which could potentially be affectedby the passing flow of blood is substantially reduced.

[0109] In an alternate embodiment of the present invention, theproximal-most balloon-expandable wireform is preferably configured tohave a diameter in its expanded state which is slightly larger than thatof the portion of the fabric tubular structure into which it is weaved.Thus, in the illustrated embodiment in which the proximal opening of thefabric portion of the graft has a diameter of 22 mm, the proximalwireform 34 is configured with a diameter of 24 mm. By configuring thewireform to be slightly larger than the fabric into which it is woven,the fabric will be maintained in a constant state of slight tension uponexpansion of the wireform, thereby reducing the possibility of thefabric folding or oscillating in response to blood flow through thegraft.

[0110] Wireforms 36, 38 are positioned adjacent the proximal wireform 34and are spaced apart from each other such that the wireforms do notinterfere with each other in either a radially expanded or contractedstate. Thus, for example, in a preferred embodiment the valleys ofwireform 34 are located proximal of the crests of wireform 36. Thewireforms 34, 36, 38 are also aligned “in phase,” with peaks along onelongitudinal line and adjacent valleys aligned along a secondlongitudinal line, thereby further reducing the possibility of overlapof adjacent wireforms. (While there may be some overlapping of the tailsegments 62 with an adjacent wireform, because the tail segments extendon the outside of the fabric layer and the adjacent wireform isprimarily on the inside of the fabric layer, a small degree of overlapwith an adjacent wireform does not pose a problem.)

[0111] In addition, adjacent balloon-expandable wireforms are notconnected to one another. This coupled with the in-phase configurationof the wireforms maximizes flexibility of the aortic graft withoutpermitting deleterious kinking, which is of primary importance in theoften tortuous paths of the abdominal aorta and iliac arteries.

[0112] The proximal three wireforms 34, 36, 38 are preferably positionedas close to each other as possible without overlapping. In thisembodiment, the wireforms 34, 36, 38 are positioned along the length ofthe graft about every 4.0 mm. By minimizing the space between theproximal three wireforms 34, 36, 38, the force exerted against the wallof the body lumen is enhanced. Thus, to the extent that the lumensurrounding these three wireforms is healthy and not expanded due to theaneurysm, the wireforms 34, 36, 38 will all assist in achieving africtional interface with the proximal end of the graft in the lumen.

[0113] The distal balloon-expandable wireform 40 is configured similarlyto the other balloon-expandable wireforms 34, 36, and 38 in that all aregenerally circular in cross section.

[0114] The distal balloon-expandable wireform 40 is attached to thefabric structure 18 in a different manner from the otherballoon-expandable wireforms. Instead of being woven into the fabricstructure 18, distal wireform 40 is attached to the fabric by tying itto the fabric with polyester thread. Other biocompatible threads mayalso be employed for securing the distal wireform 40 to the fabrictubular structure 18. In this preferred embodiment, each crest 50 ofdistal wireform 40 is secured to the fabric. Each intermediate segment56 of distal wireform 40 is also preferably tied to the fabric at apoint approximately midway between the crest 50 and an adjacent valley52. Although in this preferred embodiment, wireform 40 is tied to thefabric structure with a thread, one of skill in the art will readilyidentify other attachment methods. Adhesives, for example, may besuccessfully employed in accordance with the teachings of the presentinvention.

[0115] Distal wireform 40 is preferably positioned in the transitionregion 66 to aid in keeping the graft open. In this preferredembodiment, the distal wireform 40 is located approximately 15 mm belowthe proximally adjacent wireform 38. By positioning the distal wireform40 in the transition region 66, it will generally be located within theaneurysmic sack when the graft is properly implanted within the lumen ofa patient. Consequently, the distal wireform 40 will not engage the wallof the lumen and serves only to provide structural rigidity to maintainthe graft open at the transition region 66. Thus, it is preferable thatthe distal wireform 40 be positioned along the outside of the fabricstructure whereas the other balloon-expandable wireforms are primarilylocated inside of the fabric structure. With the wireform 40 on theoutside of the fabric structure, the wireform does not interfere withblood flow through the graft. In addition, it can not be inadvertentlysnagged from the inside as modular components are introduced into thelumen of the bifurcated graft.

[0116] In addition to the balloon-expandable wireforms 30 discussedabove, the graft 10 of the present invention also includes a number ofself-expanding wireforms 32. The configuration of each of theself-expanding wireforms 32 is naturally biased towards an expandedstate, such as that illustrated in FIG. 1. The self-expanding wireforms32 may be made of the same base material used in the construction of theballoon-expandable wireforms 30, although the method of manufacturingmay differ. Thus, ELGILOY wire is preferred, with a number of othermaterials acceptable for such use. As illustrated in FIG. 1, theself-expanding wireforms 32 employed in the graft 10 of the presentinvention have a generally curvilinear configuration having loops whichdefine crests 70 and valleys 72. Further, the intermediate sections 74are not straight, but have an “S” shape along their length.

[0117] The self-expanding wireforms 32 are constructed by obtaining coldworked ELGILOY wire having a diameter of preferably about 0.012 inchesand wrapping it around a cylindrical form 78, such as that illustratedin FIG. 1A, having primary pins 80 positioned to form the loops whichdefine the crests 70 and valleys 72 of the wireform. Two secondary pins82 are positioned adjacent each primary pin 80 to aid in defining theloops and configuring the “S” shape in the intermediate region 74 of thewireform.

[0118] The wireform is thus positioned about the entire circumference ofthe form 78 and the ends may be fitted with a crimping sleeve whilepositioned in an overlapping configuration. With the wireform thusconfigured on the form 78, the wireform and form are placed in an ovenheated to about 500 degrees centigrade for about 3.5 to about 5.0 hours.By thus heat treating the self-expanding wireform 32, the wireform willdevelop a memory corresponding to the shape in which it is positioned onthe form. Thus, the wireform may be elastically deformed, such as byradially compressing the wireform for intraluminal insertion into apatient, and, when released, will resiliently return to the shape it hadduring the heat treatment.

[0119] As an alternative method for constructing the self-expandingwireforms 32 of the present invention. a form comprising a flat surface(not illustrated) with a similar pin configuration may be utilized.After heat treating the wireform, the ends of the wireform may beattached, thereby forming the wireform into its cylindricalconfiguration, according to any of those methods described above.

[0120] As the self-expanding wireforms resiliently move between theirexpanded and contracted positions, tension is applied to the outerportion of the resulting wireform loop and a corresponding compressionresults on the inner portion of the wireform loop. Thus, the pins 80, 82of the form 78 are selected to have a radius such that the resultingtension and compression on the loop stay below the yield point of thewire. It has been found that for the preferred embodiment of theself-expanding wireforms 32 illustrated in FIG. 1, a pin diameter ofabout 0.070 inches is satisfactory and presently preferred.

[0121] The self-expanding wireforms 32 are advantageously configuredsuch that the intermediate regions 74 of the wireforms are in an “S”shape. As the wireform moves between its expanded and contractedpositions, the elastic deformation which occurs to accommodate suchmovement is spread substantially evenly throughout the entire length ofthe wireform. Consequently, the entire length of the wireform acts as aspring to help restore the wireform to its original configuration afterradial compression. Thus, the elastic deformation is not concentratedsolely in the loops defining the crests and valleys of the wireform, butis also absorbed by the intermediate segments. This reduces thepotential for exceeding the yield point of the wire at the crest andvalleys of the wireform, which would cause plastic deformation andprevent the wireform from functioning as intended.

[0122] With the self-expanding wireforms 32 formed according to one ofthe methods described above, they may be attached to the fabric tubularstructure 18 of the graft 11. Attachment of the self-expanding wireforms32 is preferably accomplished by tying the crests 70 and valleys 72 tothe fabric, as illustrated in FIG. 1. It is presently preferred thateach crest and valley be tied in five separate locations around theperimeter of the loop defining the respective crest or valley.

[0123] The self-expanding wireforms 32 are designed to have an initialexpanded diameter which is slightly larger than the diameter of thatportion of the graft where they are to be positioned. It is presentlypreferred that the wireform be about 2.0 mm larger in diameter than thecross section of fabric to which it is attached. By configuring thewireform with such a relative diameter, the self-expanding wireforms 32,when fully expanded, maintain the fabric structure to which they areattached in a state of slight tension, thereby ensuring that the fabricstructure (defining the artificial lumen) is fully open.

[0124] Further, the distal self-expandable wireforms exert a radiallyinward force against the balloon-expandable portions of the graftextensions engaged therewith, as will be described in more detail belowwith respect to the discussion of placement of the graft extensions.

[0125] When designing the wireform, it must also be recognized that thewireform will lose about five percent of its recoil ability after beingradially compressed into its state of reduced diameter and subsequentlyexpanded. Thus, for a wireform which is to be positioned at the distalend of either the 13 mm diameter contralateral leg 14 or ipsilateral leg16, the wireform will initially be designed to have a diameter of about15.7 mm. After the wireform has been radially compressed andsubsequently expanded in a body lumen, it will expand to a diameter ofabout 14.5 mm—slightly larger than the 13 mm fabric lumen provided atthe leg, as desired.

[0126] The most proximal self-expanding wireform 42 is positioned at theseptum region 28 of the graft. Wireform 42 thus acts to maintain theseptum region 28 of the graft open as blood flows through the graft. Inthis preferred embodiment, the proximal self-expanding wireform 42 islocated about 6 to 10 mm distal of the adjacent balloon-expandablewireform 40.

[0127] As illustrated in FIG. 1, at the septum region 28 of the aorticgraft, the ends of self-expanding septum wireform 42 are secured incrimping sleeves 84, 85. These crimping sleeves are of an outer diametersuch that they provide a second function as radiopaque markers. It hasbeen found that for the preferred embodiment of the crimps 84, 85illustrated in FIG. 1, an outer diameter of at least 0.036 inches issatisfactory and presently preferred. The configuration of thesecrimping sleeves aids in proper orientation of the aortic graft andconfirmation of the location of the septum within the abdominal aorta.The wireform 44 on contralateral leg 14 and wireform 46 on ipsilateralleg 16, similarly include crimping sleeve 86.

[0128] Each of the self-expanding wireforms 32 is positioned exteriorlyof the fabric tubular structure 18, thereby avoiding interference withblood flow within the graft, and preventing the wireforms from beinginadvertently snagged from the inside as modular components areintroduced into the lumen of the bifurcated graft. Additionally, theattachment of graft extensions to contralateral leg 14 and ipsilateralleg 16 (explained below) is facilitated by having the wireformpositioned on the outside portion of the fabric leg.

[0129] The graft 10 is further configured with laterally extendingreinforcement wires 90, disposed on each leg 14, 16. The wires 90 arepreferably made of the same base material as the wireforms. The wires 90are positioned on each leg 14, 16 and extend generally from a valley 72on wireform 42 to a corresponding crest 70 on a respective one ofwireforms 44 and 46. As illustrated in FIG. 1, the reinforcement wires90 are tied onto the fabric structure 18 in a similar manner as arewireforms 32, taking care that the wire 90 does not longitudinally crossinto any of the wireforms. The reinforcement wire 90 keeps the legs ofthe wireform from folding or buckling.

[0130] These two longitudinal wireforms 90 are also provided withradiopaque crimps 91 which assist in the placement of the extensiongrafts within legs 14 and 16.

[0131] C. Main Catheter Assembly

[0132] The main catheter assembly is utilized to place the aortic graftdescribed above, which is compressed and loaded onto the distal end ofthe main catheter assembly as will be described in more detail below. Amain catheter assembly useful in the practice of the present inventionis described in co-pending U.S. patent application Ser. No. 08/713,070filed on Sep. 12, 1996, previously incorporated herein by referencehereinabove (the '070 Application).

[0133] The sheath assembly 132 is utilized to facilitate the operativeplacement of the main catheter assembly. As such, the main catheterassembly is sized such that it will fit inside the introducer sheath134.

[0134] The primary components of the main catheter assembly 180 may beobserved by reference to FIGS. 4 and 6. The catheter assembly of thepresent invention comprises a rigid loader 200 which is used tofacilitate the operative coupling of the catheter assembly to theintroducer assembly during use of the present endovascular deliverysystem, as will be described in more detail with reference to FIGS. 9Band 9C. The loader comprises an elongate tube 202 including a lumen, aproximal end, and a distal end which is defined by a reduced diameterdistal section. An internally threaded connector nut 204 is attached tothe distal portion of the elongate tube.

[0135] The catheter assembly is cooperatively engaged and secured to thehead of the introducer sheath assembly by initially inserting the distalsection of the loader into the valve head of the sheath assemblysubsequent to the removal of the dilator from therewithin. FIG. 7Aillustrates insertion of the main catheter assembly into the valve headof the sheath assembly. More particularly, the distal section of theloader 200 is extended into the threaded connector 144 of the valve head136 with the connector nut being threadably engaged to the externallythreaded proximal portion of the threaded connector 144. FIG. 7Billustrates the connector nut 204 connected to the valve head 136 of thesheath assembly 132.

[0136] The loader and corresponding receiving portion of the valve headare preferably formed of rigid material such that the loader will seatcorrectly within the interfacing portion of the valve head withoutflexing or distortion thereof. This ensures proper positioning andregistry of the loader and the valve head relative to each other.Furthermore. the ability of the loader to be positively engaged, thatis, locked by threadable engagement of the nut to the valve head of theintroducer assembly, also facilitates and maintains proper registry andpositioning of the loader relative to the introducer assembly.

[0137] The catheter assembly of the present invention further includes aproximal connector assembly 206 (FIGS. 4 and 6). The proximal connectorassembly includes a pusher connector 182, which is preferably aY-connector. The proximal connector assembly 206 further includes atubular body 210 having a lumen extending longitudinally therethroughthat is ultimately in fluid communication with the interior of theballoon 194. A tubular side arm 214, which communicates with the lumenof the tubular body, is connected to the tubular body and extendsangularly therefrom. A stopcock 218 on the end of the tubular side arm214 permits valving of the balloon inflation lumen. The proximalconnector additionally comprises a Y-connector 208 and a contrastconnector 212.

[0138] The main catheter assembly 180 further comprises an elongate,tubular pusher body 184. The pusher body 184 includes a distal end 186,a proximal end 188, and a lumen extending longitudinally therethrough.The outer diameter of the distal section slightly exceeds that of theremainder of the pusher body. The proximal end 188 is operativelyconnected to the pusher connector 182, which along with the pusher body,will expel the loaded aortic graft to leave it in place within the aortaas will be described in more detail below with respect to the preferredmethod of the present invention.

[0139] The main catheter assembly of the present invention furthercomprises an elongate catheter with a coaxial tube construction. Asillustrated in FIG. 6, the elongate coaxial tube catheter comprises anelongate outer tube 190 and an elongate inner tube 192. The outercatheter defines a distal end, a proximal end, and hollow lumenextending longitudinally therethrough. The inner tube is smaller indiameter than the outer tube and extends through the lumen thereof. Theinner tube defines a distal end, a proximal end, and hollow lumenextending longitudinally therethrough. The inner tube is slidablyextensible distally and retractable proximally relative to the outertube.

[0140] The main catheter assembly further comprises an elongate,inflatable catheter balloon 194, illustrated in its inflatedconfiguration in FIG. 6. This inflatable balloon serves to expand theballoon-expandable reinforcement wires of the aortic graft. When fullyinflated, the balloon of the catheter assembly has a generally uniform,cylindrical configuration.

[0141] The balloon includes a distal end which is attached to a tubularsleeve portion 196 of the inner tube 192, and a proximal end which isattached to the outer tube 190. In turn, the extension of the inner tubedistally relative to the outer tube facilitates the longitudinalstretching of the balloon. The catheter also includes a spacer clip 198which allows the balloon to be extended or lengthened after deflationthereof to facilitate withdrawal of the balloon and catheter from theexpanded aortic graft. The inner tube is initially oriented in a firstretracted position relative to the outer tube. The balloon is inflatedonly when the inner tube is in its retracted orientation.

[0142] Subsequent to being deflated, the balloon is preferably stretchedlongitudinally by the distal advancement of the inner tube of thecatheter relative to the outer tube thereof. More particularly, theinner tube is moved from its first, retracted position to its secondextended position. The movement of the inner tube from its retractedposition to its extended position to stretch the balloon is facilitatedby tightly grasping the balloon and contrast connectors of the proximalconnector assembly, and subsequently pushing the contrast connectordistally toward the balloon connector. Since the outer tube is rigidlyattached to the balloon connector and the inner tube is rigidly attachedto the contrast connector via the sheath, movement of the contrastconnector toward the balloon connector results in a slideableadvancement of the inner tube distally within the outer tube. As aresult, the attachment of the spacer clip to the exposed portion of thesheath prevents the contrast connector from being moved distally towardthe balloon connector. While the spacer clip is in its operativeposition upon the sheath, the balloon cannot be longitudinally stretchedin that the inner tube is prevented from moving from its first,retracted position to its second, extended position. Once the spacerclip is detached from the sheath, the balloon and contrast connectorsare no longer maintained in spaced relation to each other so that thecontrast connector can be pushed distally toward the balloon connector,thereby facilitating the distal advancement of the inner tube to itsextended position and the resultant stretching of the deflated balloon.

[0143] The downstream end of the graft ipsilateral leg is trappedbetween the distal section of the pusher body and the balloon cathetershaft. This facilitates reorientation of the graft during deployment, ifdesired.

[0144] D. Main Graft Deployment

[0145] The method for using the main catheter assembly following thewithdrawal of the dilator from within the sheath assembly will now bedescribed. Initially, with reference to FIG. 10A, the main catheterassembly 180 is inserted over the primary guidewire 128 and into thesheath assembly 132. The distal connector nut 204 is connected to thethreaded sleeve portion of the valve head 136.

[0146] With reference to FIGS. 10A and 10B, the main catheter is thenadvanced over the guidewire 128 and within the sheath 134 such that thedistal-most portion extends from the sheath tip portion 138, and abovethe renal arteries 106, 108. To accomplish this, the pusher body 184(FIG. 4) is distally advanced through the lumen of the introducer sheath134 until such time as the collapsed graft 10 protrudes from the distalend of the sheath 138. More specifically, as seen in FIG. 10B, thedistal end 194 a of balloon 194 and the inner catheter 192 protrude fromthe sheath 134. The precise positioning of the main catheter in thismanner is facilitated by observing under fluoroscopy the relativepositions of a contrast marker associated with the balloon distal end194 a and the radiopaque marker 139 in sheath tip portion 138. The tworadiopaque markers 139, 194 a are brought together, with the combinationbeing relatively located with respect to the renal arteries.

[0147] The position of the sheath 134 across the aneurysm 114 permitsthe shielded introduction of the main catheter with balloon 194 andgraft 10 thereon into the proper implantation position. In other words,the surrounding sheath 134 shields the advancing catheter and theotherwise expanded and irregularly shaped graft 10 from blood flowresistance. Moreover, the sheath 134 protects the graft assembly fromcontacting the vessel walls to prevent potential snags. In short, theinitial positioning of the sheath upstream of the location at which thegraft will be finally implanted ensures that the expanded graft willonly have to be displaced downstream into its final location, which isin the direction of blood flow and thus this operation is substantiallyeasier to effectuate and is also less prone to inflict damage on thevessel walls.

[0148] Once the graft 10, still within the sheath 134, is positionedupstream from its final location the sheath is removed. FIGS. 10C and10D illustrate this operation. To accomplish this, the pusher body 184(FIG. 4) is held stationary as the sheath 134 is withdrawn from the maincatheter to a position just downstream from the graft 10. Desirably, asseen in FIG. 10D, the sheath 134 is withdrawn so that the tip portion138 is just downstream from the longer of the contralateral leg 14 oripsalateral leg 16. In the case of an enlarged aneurysm 114 as shown,the tip portion 138 will still be within the aneurysm. As the introducersheath assembly is withdrawn, the self-expanding wireforms 42, 44, & 46(FIG. 1) in the aortic graft expand within the aneurysm sack, while theballoon-expandable wireforms 30 maintain a substantially compressedconfiguration.

[0149] A final step of positioning of the graft 10 may be required. Thatis, removal of the sheath 134 from over the graft 10, as seen in FIG.10C, may leave the distal end of the graft (and distal end of balloon194 a) upstream of the renal arteries 106, 108. (In some instances,removal of the sheath 134 will, by friction, pull the main catheter andgraft 10 along with it, though the surgeon is instructed to maintain thecatheter position with the pusher body 184. In this respect, the initialpositioning of the distal end of the entire assembly upstream of therenal arteries is intended to provide some margin for downstreammovement of the catheter). If the contrast marker at the balloon distalend 194 a remains upstream of or adjacent to the renal arteries 106,108, the main catheter is then withdrawn further downstream toreposition the balloon distal end just downstream of the renal arteries.This final position is seen in FIG. 10D. The inflation balloon 194 canbe seen in outline inside of the aortic graft 10. The final displacementof the expanded graft 10 downstream is with the blood flow and thus doesnot require much force.

[0150] As seen in FIG. 10D, the graft 10 is sized such that the distalend (as carried on the catheter) thereof protrudes beyond the upstreamboundary of the aortic aneurysm and into unaffected region of theabdominal aorta 100. Locating the distal end of the graft 10 just below(downstream from) the renal arteries 106, 108 ensures the maximum lengthof contact between the eventually expanded graft 10 and the unaffectedabdominal aortic wall. The contralateral leg 14 and ipsalateral leg 16of the graft 10 extend into the aneurysm 114, and, as will be detailedbelow, extensions thereto are used to continue their respective lumensat least to the unaffected regions of the iliac arteries 102, 104.

[0151] As seen in FIGS. 11A and 11B, the balloon 194 is then inflatedvia the balloon connector. The inflation/pressurization of the ballooncauses radial expansion of the trunk portion 12 of the graft 10 from itsinitial, collapsed orientation, to its second, expanded orientation. Dueto the configuration of the balloon when fully inflated, the radialexpansion of the trunk portion 12 to its second, expanded orientation isuniform. In this respect, the expansion forces applied to the opposedends of the trunk portion 12 by the balloon are equal to those appliedto the remainder thereof. This uniform application of expansion forcesto the trunk portion 12 facilitates the tight engagement of the opposedends thereof to the luminal surface of the aorta. Preferably, theballoon is inflated for 30 seconds to a pressure of about 2 atmospheres.FIG. 11A, for example, illustrates inflated balloon 194 within theexpanded aortic graft 10 (in outline). Further, as illustrated in moredetail in FIG. 11B, balloon 194 may be slightly over-sized (representedby the arrows pointing outwardly from the balloon) to force aortic graft10 into optimal engagement with the aortic wall, especially given thetendency of the wireforms to recoil inwardly slightly after expansion.When the graft is fully expanded, the opposed ends thereof frictionallyengage the luminal surfaces of unaffected regions of the aorta.

[0152] After the graft has been radially expanded in the aforementionedmanner the balloon is deflated and removed from within the sheath 134.As illustrated in FIG. 12A, the balloon 194 is deflated and the stopcock218 is left open to room air to equalize negative pressure. When theballoon 194 is deflated it may not return to its initial, uninflatedorientation due to rigidity of the balloon material. Rather, thediameter of the main body portion of the deflated balloon may remainsubstantially the same as when the balloon is fully inflated, or mayotherwise continue to protrude in a manner that could complicatesubsequent retraction and removal of the delivery catheter.

[0153] To prevent the deflated balloon 194 from inadvertently catchingon or interfering with the radially expanded graft 10 during thewithdrawal of the balloon from within, the balloon is longitudinallystretched prior to the withdrawal of the main catheter from within thegraft as seen in FIG. 12B. As previously explained, such stretching ofthe deflated balloon is accomplished by distally advancing the innertube 192 of the main catheter relative to the outer tube 190 thereofSuch movement of the inner tube is facilitated by tightly grasping theballoon and contrast connectors of the proximal connector assembly withthe spacer clip removed, and subsequently pushing the contrast connectordistally toward the balloon connector, which pushes the distal end ofthe balloon in the direction indicated by the arrow 216 in FIG. 12B. Avacuum may be pulled through stopcock 218 to completely deflate theballoon 194.

[0154] The main catheter with the now deflated and stretched balloon 194is then withdrawn slowly and carefully from the aortic graft and intothe introducer sheath as illustrated in FIG. 12C. Once the main catheterassembly has been proximally retracted into the introducer sheath 134,it is withdrawn from within the patient's body as indicated by arrow217. The aortic graft 10 remains in place within the abdominal aortawith the introducer sheath 134 still in position just downstreamthereof, and the primary guidewire 128 extending therethrough. It shouldbe noted that the blood flow down the abdominal artery 100 now flowscompletely through the graft 10; that is, through the trunk 12 and twolegs 14 and 16. Attachment of the extensions inside the legs must adaptto this flow, as will be described below.

[0155] E. Extension Grafts

[0156] As previously described hereinabove, the downstream end of theaortic graft 10 is bifurcated with a septum region 28 separating theipsilateral leg 16 from the contralateral leg 14. Two additional graftportions are adapted to extend into the respective iliac arteries and toform a frictional engagement with the ipsilateral and contralateral legsof the aortic graft.

[0157] These extension grafts typically comprise straight or taperedcylindrical tubes, with an upstream end having a common diameter, whilethe diameter of the downstream ends can vary depending on the anatomy ofthe patient. The upstream ends interlock with the respective downstreamportions of the aortic graft. By fixing the diameter of the upstreamends of the extension graft and the downstream ends of the bifurcatedaortic graft, a consistent interface and interlock can be achievedregardless of the patients anatomy. The diameter of the downstream endof the graft extensions can be provided in varying diameters so as tosuit the diameter of the iliac artery into which graft portions arebeing implanted. The change in diameter can be provided by a shortstep-down portion or a step-up portion or by a region of taper extendingalong a length of the graft portion.

[0158] Turning now to FIG. 2, one preferred embodiment of a graftextension 170 is depicted. The graft extension comprises an upstreamportion 172, a downstream portion 174, and a lumen running the lengththereof.

[0159] In a preferred embodiment the graft extension 170 is configuredfrom a flexible tubular 175 structure which is reinforced by wireforms176 extending circumferentially around the tubular structure. Theflexible tubular structure is foldable and the wireforms are radiallycompressible and expandable. Thus, the extension graft is configured tomove between an insertion diameter, in which state the graft may beinserted through a femoral and iliac artery and into one of thebifurcated legs of the aortic graft, and a larger, expanded diameter(illustrated in FIG. 2) in which state the graft may be secured withinthe aortic graft.

[0160] In the expanded state illustrated in FIG. 2, the extension graft170 is generally cylindrical and may be configured to be a variety ofsizes, one of which is selected according to the size of the iliacartery of the patient into which the extension graft is to be implanted.

[0161] The flexible tubular structure 175 is preferably made of a tubeof woven polyester fabric. Although polyester is presently preferred,other materials may be utilized for the flexible tubular structure 175.Such materials include but are not limited to expandedpolytetrafluoroethylene (ePTFE), coated polyester, porous polyurethane,silicone, and spun or woven polymeric fibers. One of skill in the art ofbiocompatible grafts will readily identify other materials suitable forapplication in the construction of the flexible tubular structure 175.It is preferred that the tubular structure be made of a material whichis porous, thereby allowing tissue ingrowth into the graft materialand/or formation of an intimal layer, although for some applications itmay be desirable to make the tubular structure of a fluid imperviousmaterial.

[0162] Preferably, the fabric is woven into the tubular configuration,thereby eliminating seams or other internal protrusions which couldinterfere with blood flow or form locations for thrombi to occur. Byemploying a flexible fabric for the tubular structure, the fabric willreadily fold to accommodate radial contraction of the graft, such as isnecessary for intraluminal introduction of the graft.

[0163] In one preferred embodiment of the present invention, thediameter of the fabric tubing of the graft is over-sized with respect tothe wire-forms therewithin. Upon balloon-expansion of theballoon-expandable wireforms, there is a small amount of recoil thatoccurs in the wireforms. The fabric tubing of the graft therefore canhave a diameter which is larger than the post-recoil diameter of thewireforms. In turn, the wireforms can be over-expanded with a secondballoon of a different size such that upon recoil, the diameter of thewireforms is of the proper size for optimum retention of the graftwithin the vessel. This feature enables a surgeon to optimize the fit ofa graft within a vessel without having to remove a too-small graft andreplace it with another. That is, a graft which upon firstballoon-expansion may not sufficiently engage with wall of vessel, maybe subsequently over-expanded by a second balloon of a larger size tooptimize the fit therein.

[0164] In accordance with a presently preferred embodiment of theinvention, a number of balloon-expandable wireforms 176 are provided tofurnish structural rigidity to the graft and to secure the graft withinthe body lumen. Each of the balloon-expandable wireforms is similarlyconfigured with a curvilinear geometry such as the closedsinusoidal-like wave geometry illustrated in FIG. 2A, with alternatingcrests 150 and valleys 152 which define an amplitude 154. The amplitude154 of a wireform is thus defined as the longitudinal distance between acrest 150 and an adjacent valley 152.

[0165] Alternatively, the balloon-expandable wireforms are configuredsuch that they are continuously curvilinear, such as the configurationof the wireform illustrated by FIG. 1B. As noted above, thiscontinuously curvilinear shape 48 reduces stress on the wireforms whenthe graft is in its first, compressed state.

[0166] An alternative method for constructing the balloon-expandablewireforms is to configure the wireforms in a true sinusoidal pattern.One of skill in the art will be familiar with other methods formanufacturing balloon-expandable wireforms without departing from theteachings of the present invention.

[0167] The balloon-expandable wireforms 176 are preferably configuredwith a plurality of intermediate segments 156 which are connected bycorresponding crests 150 and valleys 152. The crests 150 and valleys 152are formed with a radius which, in this preferred embodiment, is about0.025 inches.

[0168] Preferably, the intermediate segments are positioned at an anglewith respect to each other of greater than about 90 degrees in order toprovide greater wireform rigidity, reduced wireform recoil, andincreased anchoring force. To those ends the intermediate segments aremore preferably positioned at an angle with respect to each other from arange of about 100 degrees to about 135 degrees. Most preferably, theintermediate segments are positioned at an angle with respect to eachother from a range of about 120 degrees to about 125 degrees.

[0169] The balloon-expandable wireforms 176 of the present invention arepreferably made of an alloy of carbon, silicon, phosphorus, sulphur,chromium, nickel, beryllium, cobalt, iron, manganese and molybdenumwhich is sold under the ELGILOY trade name by Elgiloy, L.P. of Elgin,Ill., U.S.A. Other materials which may be utilized in making thewireforms include a nickel-titanium shape memory alloy sold under theNITINOL trade name, stainless steel, and other biocompatible,implantable metals. The wires used in manufacturing theballoon-expandable wireforms of the present invention are preferablyabout 0.012 inches in diameter.

[0170] Because the wire has been annealed, it will readily plasticallydeform to maintain its configuration. Thus, the wireform may beplastically deformed between the radially collapsed position and theradially expanded position of FIG. 2. The wireforms are, therefore, notresilient to any substantial extent, requiring them to be physicallyexpanded into contact with the internal wall of the iliac artery anddownstream legs of the aortic graft via an external force rather thanexpanding by virtue of their own resilience.

[0171] The balloon-expandable wireforms which are positioned along thegraft extension are preferably secured to the fabric graft material byweaving the wireform through the fabric material. The wire is weavedthrough the fabric such that the distal tip of the valley of eachwireform extends through the graft and is positioned on the outside ofthe fabric structure. The weaving is accomplished by initiallyconfiguring an elongated piece of wire into the predeterminedcurvilinear configuration. With the wire so configured, it may bemanually woven through the fabric structure until the wire extendsaround the entire circumference of the fabric structure. The wire iswoven such that it is primarily positioned along the interior of thefabric tube, with only small segments of wire exposed to the outside ofthe tube.

[0172] The wireform is woven into the fabric tube such that when thewire extends around the entire periphery of the fabric tube, the freeends of the wire protrude from the tube at positions adjacent to eachother, thereby enabling a tail segment 177 to be defined by the freeends. The loose ends are preferably held together with a crimping sleeve178 positioned over them. After crimping the sleeve to secure the endsto each other and thereby complete the circular configuration of thewireform, any portion of the wires extending beyond the ends of thesleeve may be trimmed to cleanly finish the tail segment.

[0173] As illustrated in FIG. 2, the crimping sleeves extend outwardlyalong the external surface of the extension graft and are radiallyspaced apart. Preferably, the crimping sleeves on the upstream portion172 of the extension graft face in a downstream direction, thusfrictionally engaging with the wall of the aortic graft body which helpsto hold the extension into place. In fact, these upstream crimpingsleeves can actually hook on the interior surface of the primarybifurcated graft, thus ensuring no longitudinal movement or separationof the extension graft from the primary aortic graft. The crimpingsleeves on the downstream portion 174 face upstream and may frictionallyengage, but not penetrate, the wall of the vessel lumen within which thedevice is placed. The crimping sleeves act as radiopaque markers,particularly for aiding in the placement and positioning of the graftextensions.

[0174] The most proximal wireform 168 and the most distal wireform 166are positioned with respect to the upper and lower edge of the fabriclayer such that approximately one-third of the wireform extends beyondthe respective edge of the fabric layer In particular, the proximal-mostwireform is positioned to extend above the edge of the fabric layer toprevent any portion of the fabric layer from oscillating, or “flapping,”in response to the flow of blood past the edge of the graft. As anadditional measure to prevent such fabric oscillation in the bloodstream, the proximal and distal edges of the fabric are configured withV-shaped notches corresponding generally to the valleys 152 of theproximal and distal wireforms. Thus, the risk of the existence of anyloose fabric which could potentially be affected by the passing flow ofblood is substantially reduced.

[0175] In an alternate embodiment of the present invention, theproximal-most balloon-expandable wireform is preferably configured tohave a diameter in its expanded state which is slightly larger than thatof the portion of the fabric tubular structure into which it is weaved.By configuring the wireform to be slightly larger than the fabric intowhich it is woven, the fabric will be maintained in a constant state ofslight tension upon expansion of the wireform, thereby reducing thepossibility of the fabric folding or oscillating in response to bloodflow through the graft.

[0176] Additionally, the proximal balloon-expandable wireforms on thegraft extension work in concert with the distal self-expandablewireforms on the aortic graft to hold the graft extensions in place. Theballoon-expandable wires can be expanded slightly beyond the diameter ofthe distal self-expandable wireforms. This will cause the distalself-expandable wireforms to exert a radially inward pressure againstthe balloon-expandable portions of the graft extensions, therebyenhancing the frictional interface between them and providing a tighterseal.

[0177] In a preferred embodiment of the present invention, the wireformsare positioned adjacent one another and are spaced apart from each othersuch that the wireforms do not interfere with each other in either aradially expanded or contracted state. Thus, for example, the valleys ofone wireform are located proximal of the crests of the next adjacentwireform. Preferably, the wireforms are also aligned “in phase,” withpeaks along one longitudinal line and adjacent valleys aligned along asecond longitudinal line, thereby further reducing the possibility ofoverlap of adjacent wireforms. (While there may be some overlapping ofthe tail segments with an adjacent wireform, because the tail segmentsextend on the outside of the fabric layer and the adjacent wireform isprimarily on the inside of the fabric layer, a small degree of overlapwith an adjacent wireform does not pose a problem.)

[0178] In addition, adjacent balloon-expandable wireforms are notconnected to one another. This coupled with the in-phase configurationof the wireforms maximizes flexibility of the aortic graft withoutpermitting deleterious kinking, which is of primary importance in theoften tortuous paths of the abdominal aorta and iliac arteries.

[0179] An important feature of the extension grafts of the presentinvention is the spacing distance between adjacent wireforms. It hasbeen discovered in accordance with the investigations of the presentinvention that optimizing the spacing distance between the wireformsimproves the balance between kink resistance and flexibility in thegraft extensions. Too much space promotes kinking, while too littlespace detracts from flexibility. These are important features in theoften tortuous path of the iliac arteries and abdominal aorta in whichthe graft extensions are to be placed.

[0180]FIG. 2A, for example, illustrates in cross-sectionballoon-expandable wireforms 176. Preferably the length “L” orseparation distance between adjacent wireforms is measured from theclosest point on each neighboring wire. For example, in FIG. 2A, L isthe distance between crest 150 and valley 152.

[0181] Further, the graft extensions have a diameter “D” which variesaccording to the differently sized extensions. In one embodiment thelength L between adjacent wireforms is preferably less than 2D. In apreferred embodiment the length L between adjacent wireforms will beless than D. In another preferred embodiment the length between adjacentwireforms will be less than D and greater than zero. Therefore, thepreferred separation distance depends on the diameter of the graft.

[0182] In a 14 mm graft a preferred separation distance between adjacentwireforms that has been found to be acceptable during use is 2.4 to 2.5mm.

[0183] Further, as discussed above, the interface between the upstreamportion of the extension graft and the downstream leg of the aorticgraft is preferably standardized such that the downstream legs and theupstream extensions have the same dimension at their interface,regardless of the diameter of the aorta above the aneurysm and thediameters of the iliac arteries below the aneurysm.

[0184] F. Directional Catheter

[0185] The present invention further includes a directional catheter.The structure of this catheter is substantially disclosed in WO97/26936, which was previously incorporated by reference hereinabove.Specifically, the directional catheter facilitates guidewire access tothe contralateral leg of the bifurcated graft to allow placement of acontralateral extension graft into the bifurcated graft.

[0186] The primary components of directional catheter 220 may beobserved by reference to FIG. 5. The directional catheter includes adeflecting spring portion 222, (illustrated substantially deflected).Knob 224 is used to deflect the spring portion. Connector nut 226 isprovided such that the directional catheter can be operatively connectedwith the sheath assembly.

[0187] G. Extension Graft Deployment

[0188] The procedure for attaching the extension tubes will now bedescribed. With reference to FIGS. 13A and 13B, the sheath 134 stiffenedby a dilator (not shown) is advanced over the guidewire 128 until thedistal tip 138 is located approximately at the septum region 28. Thelocation of the distal tip 138 is again facilitated byfluoro-visualization of the marker 139 with respect to the radiopaquecrimping sleeves 84, 85 (FIG. 1) on the graft 10. The dilator is thenproximally withdrawn from within the sheath 134, and the directionalcatheter 220 advanced distally over the guidewire 128 and within thesheath 134 to project a short distance from the distal tip 138 (FIG.13B).

[0189] More particularly, the directional catheter 220 is first insertedover the primary guidewire through the ipsilateral side, for example,through the right femoral artery 116 and the right common iliac artery102 in the present case. FIG. 13A illustrates the directional catheter220 operatively connected to the sheath assembly 132. The spring portion222 of the directional catheter 220 is positioned such that it is abovethe septal region 28 of the aortic graft 10. Proper positioning of thespring portion to the contralateral side is adjusted by rotating oradvancing forwards or backwards the whole directional catheter 220 whileunder fluoro-visualization. The spring portion 222 is deflected bypulling knob 224 in the direction of the arrow in FIG. 13A. FIG. 13Billustrates the deflected spring portion 222 positioned within thecontralateral leg 14.

[0190] A supplemental guidewire 228 is then advanced through thedirectional catheter 220 and out the deflected spring portion 222 toextend down the contralateral leg 14 and through the left common iliacartery 104. The supplemental guidewire 228 is extended until it is inthe left femoral artery 118, at which time the left femoral artery iscross-clamped and a cut-down or percutaneous incision is performed toretrieve the supplemental guidewire. If the guidewire has not beenguided fully along the femoral artery a snare or similar device can beintroduced through the left femoral artery to grab the guidewire anddraw it back to the puncture or incision site for retrieval.

[0191] As seen in FIG. 13C, once the supplemental guidewire 228 is inplace through the left common iliac artery 104 the directional catheter220 is advanced distally through the bifurcated graft 10 and into aposition above the renal arteries 106, 108. The spring portion 222remains deflected to present a curvilinear upstream profile. This curvedprofile enables advancement of the directional catheter 220 without riskof the distal end of the spring portion 222 snagging on the openings tothe renal arteries 106, 108. The directional catheter 220 remains inthis position while the tubular graft extension 170 is attached to thecontralateral leg 14. A stiffer guidewire 228 a is then exchanged withthe supplemental guidewire 228 by conventional methods to extend throughthe left iliac artery 104 and within the contralateral leg 14 of theaortic graft.

[0192] As illustrated in FIGS. 14A and 14B, a second introducer assembly230 is introduced with the help of a dilator 240 over the stiffguidewire 228 a in the manner previously described for the firstintroducer assembly 130. The dilator 240 is removed leaving a secondsheath 270 in position with its distal tip 272 adjacent the graft septumregion 28. Again, a radiopaque marker 274 on the distal tip 272 alignswith the septum region 28 and its radiopaque markers 84, 85 (FIG. 1).

[0193] As seen in FIG. 15A, a second catheter assembly, on which ispackaged the tubular graft extension 170 is then introduced through thesheath 270. A pusher body, (not shown but similar to that describedabove) pushes the tubular graft extension 170 distally within the sheath270. Again, this procedure for advancing a graft upstream with respectto the aneurysm 114 while housed within the sheath 270 is necessary toavoid difficulties associated with displacing an irregularly shapedobject against the blood flow. It is especially significant given thatthe trunk portion 12 has been expanded into contact with the abdominalaorta 100, and thus the entire blood flow through the abdominal aortacontinues through the graft legs 14, 16. Ultimately, a distal portion286 of the inflation balloon extends from the distal tip 272 of sheath270.

[0194] Once the tubular graft extension 170 is in place, the secondintroducer sheath 270 is withdrawn (as seen by the arrow 276 in FIG.15B) to a position within the left common iliac artery 104. Afterdisplacing the second introducer sheath 270, the pusher body isretracted slightly to release the proximal end of the graft extension170. FIG. 15B illustrates the compressed balloon-expandable tubulargraft extension 170 in proper position for expansion and implantation.

[0195] As illustrated in FIG. 15C, the balloon on the second catheterassembly is then inflated forcing the upstream portion of the graftextension 170 into contact with the inner surface of the contralateralleg 14, and downstream portion of the graft extension into contact withthe inner surface of the left common iliac artery 104. As with theinflation balloon 194 for the trunk portion 12 the inflation balloon forthe tubular graft extension 170 is first deflated and then stretched toremove it from within graft without snagging.

[0196] After the tubular graft extension 170 on the contralateral sidehas been expanded, the directional catheter 220 in the first introducersheath 134 is withdrawn. First, however, the spring portion 222 isstraightened to its home position (FIG. 15C) to enable the catheter 220to be retracted within the sheath 134.

[0197] As seen in FIG. 16A, a third catheter assembly on which ispackaged another tubular graft extension 170′ is then advanced over theprimary guidewire 128 and through the lumen of the sheath 134 until adistal end 296 of the inflation balloon projects slightly from thedistal tip 138. Again, a radiopaque marker on the distal end of theballoon catheter is used to place it in registry with the marker 139 onthe distal tip 138, which was previously registered with the marker atthe graft septum region 28.

[0198] The first introducer sheath 134 is slightly larger than thesecond sheath 270 because it is sized for passage of the balloon 194 ofthe first catheter assembly on which the trunk portion 12 is wrapped.For example, the inner diameter of the introducer sheath 134 may be 19French, while the inner diameter of the second sheath 270 may be 16French. As a result, there is some acceptable clearance between passageof the third catheter assembly and tubular graft extension 170′ thereonand the inner lumen of the introducer sheath 134. In this manner theintroducer sheath 134 need not be removed and replaced with a smallerone.

[0199] In the same manner as on the contralateral side, and asillustrated in FIG. 16B, first the sheath 134 and then the pusher body(not shown) are withdrawn proximally to release the tubular graftextension 170′ such that its upstream end is inside the ipsilateral leg16 of the aortic graft 10 and its downstream end is within the rightcommon iliac artery 102. The catheter balloon is inflated to force theupstream end of the graft extension 170′ into contact with the innersurface of the ipsalateral leg 16. At the same time, the balloon forcesthe downstream end of the graft extension 170′ into contact with theinner surface of the right common iliac artery 102. The final expandedposition of the tubular graft extension 170′ is seen in FIG. 16D.

[0200]FIG. 16C illustrates a cross-section of the left common iliacartery 104 with the first tubular graft extension 170 expanded intocontact therewith. As was described with respect to FIG. 2A, thewireforms 176 terminate in ends which are secured outside the extensionwall 175 with crimps 178. The crimps 178 as shown project outward fromthe wall 175 at a slight angle and provide additional friction to locatethe extension 170 within the artery 104. Advantageously, the crimps 178are not sharp and do not penetrate the vessel wall, as with some priorart grafts. Instead, the irregular surface formed by the multiple crimps178 prevents migration of the tubular graft extension 170 without damageto the wall of the artery 104.

[0201] Subsequently, the inflation balloon is deflated and thenstretched before removing it along with the third catheter assembly fromwithin the graft extension 170′.

[0202] In one embodiment of the present invention, the upstream portionsof either of the graft extensions 170, 170′ may be slightly over-sizedto maximize the frictional engagement with the downstream portions ofthe respective contralateral or ipsilateral legs 14, 16. In particular,the over-expansion of the balloon-expandable wireforms slightly beyondthe diameter of the distal self-expandable wireforms causes the distalself-expandable wireforms of the contralateral or ipsilateral legs toexert a radially inward force against the balloon-expandable portions ofthe graft extension. This resistance serves to improve the frictionalengagement between the contralateral downstream leg and the graftextension. Furthermore, the respective wireforms and associated crimps′tend to hook together to more securely couple the graft extensions 170,170′ to the respective contralateral or ipsilateral legs 14, 16.

[0203] In an alternate embodiment, colloquially known as the “kissing”technique, both the ipsilateral and contralateral balloon catheterscould remain in place during implantation of both leg extensions 170,170′. In this technique, the third catheter balloon for the ipsalateralleg extension 170′ is inflated while the second catheter balloon remainswithin the contralateral leg extension 170. In other words, while thethird catheter balloon inflates, the second catheter balloon remains inplace in the contralateral leg extension 170, and is preferably deflatedto ambient pressure but is not stretched or reduced by a vacuum. Thethird catheter balloon is subsequently deflated, stretched and removed,followed by deflation, stretching and removal of the second catheterballoon. The use of the kissing technique or the more common sequentialcontralateral-ipsalateral extension implantation technique is up to thepreference of the surgeon.

[0204] An angiographic examination may take place to determine if thegrafts are correctly placed and functioning. The second sheath assemblyand the stiff guidewires are withdrawn and the contralateral incision orpuncture is sutured. The first introducer sheath assembly is thenwithdrawn and the right femoral incision is sutured. The result is afunctioning trouser graft bridging an aneurysm as illustrated in FIG.16D.

[0205] The operation may be carried out using a general anaesthetic, anepidural anaesthetic, or in suitable cases, using only a localanaesthetic.

[0206] The present invention may be embodied in other specific formswithout departing from its spirit or essential characteristics. Thedescribed embodiments are to be considered in all respects only asillustrative and not restrictive. The scope of the invention is,therefore, indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. An intraluminal prosthesis comprising: a trousergraft having a trunk and two legs diverging in a downstream directionfrom the trunk at a septum region, the graft being formed of a graftbody having an external surface and an internal surface; at least oneballoon-expandable wireform connected to the graft body at the trunk; atleast one self-expanding wireform connected to the graft body at theseptum region; at least one self-expanding wireform connected to thegraft body in each of the two legs.
 2. The prosthesis of claim 1,wherein there are at least two balloon-expandable wireforms connected tothe graft body at the trunk, one of the balloon expandable wireformsbeing positioned external to the graft body.
 3. The prosthesis of claim1, further including a tubular extension connected to a downstream endof each of the two legs.
 4. The prosthesis of claim 3, wherein thetubular extensions each include balloon-expandable wireforms and areconnected to the downstream end of the legs in such a manner that theself-expanding wireform in each leg exerts a radially inward force onthe balloon-expandable wireform in the associated tubular extension. 5.An assembly of tubular prostheses, comprising: a first tubularprosthesis including a graft body and least one self-expanding wireform,the first tubular prosthesis terminating at a downstream end in an openmouth; a second tubular prosthesis including a graft body and at leastone balloon-expanding wireform, the second tubular prosthesisterminating at an upstream end positioned within the open mouth of thefirst tubular prosthesis, the second tubular prosthesis being expandedinto contact with the first tubular prosthesis and sufficiently fartherto outwardly stress the self-expanding wireform in the first tubularprosthesis and produce an inward compressive force on the upstream endof the second tubular prosthesis.
 6. A method of deploying a bifurcatedintraluminal prosthesis to a site of implantation defined by a mainvessel branching to two smaller vessels, comprising: endoluminallydelivering a bifurcated graft having a trunk and two legs to the site ofimplantation, the trunk being positioned within the main vessel;expanding the trunk with a balloon catheter into contact with the mainvessel; delivering a first tubular extension into position with one endwithin one of the two legs and with the other end within one of the twosmaller vessels; expanding the first tubular extension with a ballooncatheter into contact with said one of the two legs and into contactwith said one of the two smaller vessels, the first leg being expandedbeyond a relaxed state so that it imparts an inward compressive force onthe first tubular extension; delivering a second tubular extension intoposition with one end within the other of the two legs and with theother end within the other of the two smaller vessels; expanding thesecond tubular extension with a balloon catheter into contact with saidother of the two legs and into contact with said other of the twosmaller vessels, the second leg being expanded beyond a relaxed state sothat it imparts an inward compressive force on the second tubularextension.